Using sand for construction purposes.

Once I wanted to buy some sand for a repair of my house, went to few hardware stores but couldn’t get the appropriate sand which is suitable for constructions. At one place the had a muddy sand which they were recommending that it is the most high quality & appropriate sand for constructing which is brought from “Daduru Oya”. But with my experience I knew that it’s not suitable.
There was an known mason and he too was recommending that even he used this sand to build his own house and that’s the most high quality sand that I ever can find hence its River sand.
What I am trying to point out from this incident is that there are various opinions about using sand for construction’s which differs from one another, some are true &some are false.
As an example even some of the senior engineers recommend that using sea sand for construction’s is not suitable due to the salt content in it, but according to the experiment’s done by department of civil engineering of Moratuwa University they have proved that using sea sand Is a very best substitute for river sand and it doesn’t make any bad effect on the durability of the building. In a way it’s environmentally friendly as well.
Lot of people are using muddy sand telling that its river sand but since it contains a certain percentage of mud it’s not suitable for constructions.
Even there are some false statements about measuring the capacity of sand, normally we measure sand using the unit “Cube” which is equal to 100 cubic feet’s, most of the sand dealers say that once the deck of a small lorry is completely filled with sand it’s a cube, but it doesn’t contain exactly a cube, lot of consumers doesn’t know about this. To calculate the real capacity what you have to do is multiply the length of the deck by the breath & the height of it. (Length x breath x height = volume of the deck).